1. Field of the Invention
The present invention relates to a process and to a device for producing a cylindrical single crystal of semiconductor material with the smallest possible alignment error of the crystal lattice. The invention also relates to a process for cutting semiconductor wafers from two or more such single crystals by means of wire sawing.
2. The Prior Art
The crystal lattice of cylindrical single crystals of semiconductor material often has a particular alignment error. There is an alignment error if the crystal axis and the geometrical axis of the single crystal are at a certain angle. The crystal axis is an axis defining the crystallographic orientation of the crystal lattice. For the production of electronic components, it is in particular necessary to obtain silicon crystals which have, for example, a &lt;100&gt;, &lt;511&gt;, &lt;110&gt; or &lt;111&gt; crystal orientation. The spatial position of the crystal axis is determined using an X-ray optical method, for example according to the process described in German Standard DIN 50433 (part 1). The geometrical axis of a cylindrical single crystal corresponds to the long axis of the single crystal passing through the middle of the single crystal.
Usually, each single crystal needs to be examined to ascertain whether the crystal lattice has an alignment error. Section planes through the single crystal when cutting semiconductor wafers are set so as to provide semiconductor wafers having a desired crystal orientation. This process is especially elaborate and likely to cause error.